Software-defined networking (SDN) along-side with micro-segmentation has been proposed as a new paradigm to deploy applications faster and, simultaneously, protect the individual workloads against lateral movement. One of the major solutions in this area is the Application Centric Infrastructure (ACI) by Cisco. As part of our research endeavors, we performed a security assessment of Cisco ACI. In this whitepaper, we will provide an introduction to Cisco ACI, present the results of our assessment, and give recommendations on how to operate Cisco ACI more securely.